Making events invisible in time? Wow

"It’s like breaking up a line of cars at a traffic signal, and then allowing the ones that were stopped to catch up with the rest and re-form a continuous line. 

Making an object invisible in space? That’s been done. What about making one invisible in time?

At Cornell University, Alexander L. Gaeta and Moti Fridman led a team that experimented with making events invisible in time. Even though they only managed to mask a picosecond-scale event, the work points the way to making not only true cloaking devices, but better security over fiber-optic lines as well.

Scientists have been using the phenomenon of refraction for experimenting "invisibilty" since a few years now.But cloaking in time is a totally new concept, one that would grab the attentions of many.

Instead of bending light waves around an object, the Cornell team slowed the light down on one side of an object, using a “time lens” that slowed wavelengths of light (think: red, blue, indigo, violet, etc.) and caused them to arrive at their destination at different times.

By passing the light through the time lens and then through a medium that dispersed it, they were able to create a gap in the light -- a time when no wavelength was visible. First one would see the shorter wavelengths (violet to blue and green), a gap, then the longer wavelengths (yellow to orange and red).  

Next, by sending the light through another medium that reversed the dispersion and then another time lens, the beam looked just as it did before. The gap would be stitched together, with no way to know that anything had happened.

 To test their idea, the scientists sent a light pulse through the gap, at a different frequency from the reference beam. That pulse was nearly invisible.

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